/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/PBDRigidsEvolution.h
Make a copy of the acceleration structure to allow for external modification. This is needed for supporting sync operations on SQ structure from game thread. You probably want to go through solver which maintains PendingExternal
void UpdateExternalAccelerationStructure_External ( [ISpatialAccelerationCollection](API\Runtime\Engine\PhysicsEngine\ISpatialAccelerationCollection)< [FAccelerationStructureHandle](API\Runtime\Chaos\Chaos\FAccelerationStructureHandle), [FReal](API\Runtime\ChaosCore\Chaos\FReal), 3 > *& ExternalStructure, [FPendingSpatialDataQueue](API\Runtime\Chaos\Chaos\FPendingSpatialDataQueue) & PendingExternal )